Silencer



asoma? H. H. MAXNM Dec; 29, 1942.

S ILENCER Filed June 2o, 1941 INVENTOR HMAMMMILWMAXM Patented Dec. 29, 1942 SILENCER Hiram Hamilton Maxim, Hartford, Conn., assignor to The Maxim Silencer Company, Hartford, Conn., a corporation of Connecticut Application June 20, 1941, Serial No. 398,877

9I Claims.

This invention relates to silencers, and has particular reference to silencers in which sound is attenuated and gas pulses broken up by being permitted to enter or leave a chamber both through the open end of a tube and through a slot or series of perforations formed in the side of the tube. The object of the invention is to provide a silencer of this type having great simplicity in manufacture as well as certain advantages in operation. Additional objects and advantages will appear from the following description and claims.

Referring to the drawing,

Fig. l is a central longitudinal section through a silencer embodying the invention;

Fig. 2 is an end view; and

Fig. 3 is a section on line 3-3 of Fig. l.

The silencer is formed with a generally cylindrical casing I having end headers II and I2 and for best performance is proportioned so that its length is more than five times, and preferably about six times, its diameter. The cross-sectional area of the casing is preferably about five times the cross-sectional area of the size of pipe with which it is to be used. It will be understood that these relative dimensions are intended as guides, and that certain aspects of the invention may be employed in silencers of other proportions. On silencers for industrial installations the casing will be several feet long, and in order to permit the assembly of the internal structure the casing I0 is preferably formed in two parts which are subsequently welded together along the circumferential line I3 which is roughly half-way between its ends.

A tube I4, having a slot I5 or a series of perforations along its length, is welded at I6 and I'I to the members I8 and I9 of a laminated partition member and is slipped into one half of the casing before the weld is made'at I3. To avoid excessive back-pressure it is desirable to terminate the open ends of the tube a distance from the end headers on the order of the diameter of the tube, preferably slightly more than the diameter. The position of the partition is such that 11.

The tube I4 is conveniently formed by rolling up a flat sheet into cylindrical form so as to leave a slot which preferably has a width about 2% of the circumference of the tube. To hold the rolled-up tube in a rigid assembly narrow straps 2I are welded across the slot, and to hold the tube in position in the casing struts 22 are secured to it at a point near the end of the right hand half 23 of the casing. When this half is put in place and welded along the line I3, but before its header I2 is welded, the outer ends of the struts 22 are welded to the shell. The pipe Iii is thus supported at one end by the struts 22 and at an intermediate point by the composite partition I 3, I9, the further en-d being without necessity of support.

An inlet connection 25 is secured to the shell at an intermediate point along the length of the chamber 2G, which in the case shown is the longer of the two into which the casing is divided by the transverse partition. The inlet gases pass through the connection with considerable force, and in order to prevent too much of the gas from passing directly through the open end of the tube i4 (which preferably is of the same cross-sectional area as the inlet connection), the inlet is preferably located partway along the tube rather than adjacent its end, and is located at least away from the slot I5. Similar precautions, however, do not need to be taken with the exhaust connection 2'I, which in the case shown opens into the chamber 28 near the open en-d of the tube I4; this giving some reduction in back-,pressure with little adverse effect on the sound level.

For similar reasons it is desirable to laminate the chamber 26 in order to avoid shell noise, but it will in general be unnecessary to treat the chamber 28 in this manner. A cylindrical sheet 2Q is tack welded at 3l) to the nteriorvof the casing section 23, terminating slightly short of its ends to facilitate welding along the lines I3 and 3l A circular plate 32 is tack-Welded to the header I 2 for the same purpose. No laminations have been shown in the second chamber 28, and these in general will be unnecessary, since the strong gas pulses entering chamber 26 will have been broken up so greatly before they enter chamber 28 that they will not tend to cause audible vibrations of the shell and header.

In operation gas will enter the chamber 26 through connection 25 and will pass into tube I4 in part through its open end and in part through the slot I5. Entry from the tube to chamber 28 will take place in part through the slot and in part through the open end of the tube. The gases, with the sound-producing pulses and the major proportion of sound waves removed, iinally passes out the exhaust connection 2l. The nonintegral relation between the two chambels prevents standing waves in one chamber, which would practically short-circuit it for the resonant frequency, being also by-passed through the second chamber in the same way. A second inlet 33 may be used where the silencer is being used to attenuate both a main engine and a smaller auxiliary.

I claim:

l. A silencer comprising a substantially cylindrical casing having end headers, a partition dividing the casing into two chambers of unequal lengths, the length of the longer being a non-integral multiple of the length of the shorter, a slotted tube extending through the partition and terminating in an open end within each chamber at a point spaced from the end header a distance on the order of the diameter of the tube, an inlet opening laterally through the cylindrical casing into the longer of the two chambers at a point in termediate the length of the tube, and an outlet opening laterally through the cylindrical casing at a point adjacent the open end of the tube.

2. A silencer having a substantially cylindrical casing having a length substantially six times its diameter, a partition extending across the casing at a point substantially four-sevenths of the length of the casing, a slotted tube having a crosssectional area on the order of one-fth the crosssectional area of the casing, extending through the partition and terminating in open ends at t.

points spaced from the end headers a distance on the order of the diameter of the tube, an inlet opening laterally through the cylindrical wall of thel casing into the longer chamber intermediate the length of the tube, and an outlet opening laterally through the wall of the cylinder into the shorter chamber adjacent the open end of the tube.

3. A silencer having a substantially cylindrical casing having a length substantially six times its diameter, a partition extending across the casing at a point substantially four-sevenths of the length of the casing, a slotted tube having a crosssectional area on the order of one-fth the crosssectional area of the casing, extending through 't the partition and terminating in open ends at points spaced from the end headers a distance on the order of the diameter of the tube, and an inlet and an outlet opening through the cylindrical wall on the order of the diameter of the tube, and an inlet and an outlet opening through the cylindrical Wall oi the casing one into each of the chambers.

5. A silencer having a substantially cylindrical casing having end headers, a partition dividing the casing into tWo chambers of unequal lengths, the length of the longer being a non-integral multiple of the length of the shorter, a laminating lining secured within the casing and extending part Way only along the longer chamber, a slotted tube extending through the partition and terminating in an open end within each chamber at a point spaced from the end header a distance on the order of the diameter of the tube, and an inlet and an outlet opening through the wall of the casing one into each of the chambers.

6. A silencer comprising a cylindrical casing having end headers, a partition dividing the casing into two chambers, one having an inlet connection and the other an outlet connection, a slotted tube passing between the chambers through the partition and welded thereto, the casing having a circumierential welded joint in a plane adjacent the partition, and a laminating shell secured to the casing at the inlet side only of the circumferential welded joint, the end header at the inlet end of the silencer being laminated.

'7. A silencer comprising a cylindrical casing, a partition dividing the casing into two chambers, one having an inlet connection and the other an outlet connection, a slotted tube passing through the partition and welded thereto, and laminating members secured to thev inner Walls of the inlet chamber only.

8. A silencer comprising a casing having end headers and a cylindrical Wall, a partition dividing the `casing into a rst and a second chamber, an inlet conduit connecting with the rst chamber through the cylindrical wall of the casing, an outlet conduit' connecting with the second chamber through thev cylindrical wall of the casing, and an open-ended tube passing through the partition and extending into at least the exhaust chamber to a distance from the end header a distance on the order of the diameter of the tube andA overlapping said outlet conduit, said tube having a lateral escape opening in its wall within said chamber.

9. A silencer comprising a substantially cylindrical casing having end headers, a transverse partition dividing the casing into two chambers of unequal lengths, the length of the longer being a non-integral multiple of the length of the shorter, a tube with open ends extending through the partition and secured thereto, said tube having one or more lateral escape openings extending substantially throughout its length, an inlet passage extending through the cylindrical wall of the casing and opening into one of the chambers at a point intermediate the length of the tube, and an outlet. passage opening into the second chamber at a point adjacent the open end of the tube.

HIRAM HAMILTON MAXIM. 

